In various commercial and industrial applications, it is often necessary for conduits fabricated from different metals such as aluminum and steel to be joined together in fluid-flowing relation. For example, in refrigeration applications, aluminum heat exchangers are often employed because of their light weight, high thermal conductivity and good corrosion resistance as well as their low cost. Aluminum has often been selected for use in the fabrication of these heat exchangers because of their compatibility with ammonia which is a commonly used refrigerant in large industrial refrigeration systems.
Refrigerant piping in these large refrigerant systems is often fabricated from carbon steel or an iron-chromium alloy (stainless steel). In installations of this type means must be provided for connecting the aluminum heat exchangers or conduits coupled to same to the carbon steel, or stainless steel refrigerant piping. Heretofore, bolted flange union joints having dielectric gaskets and washers have been used to make these fluid coupling connections. An example of a prior art flange union joint is seen in FIG. 1.
While these bolted, flange union joints have operated with some degree of success, there are several shortcomings which have detracted from their usefulness. For example, typical dielectric bolted flange union joints usually consist of a number of parts including flanges, bolts, nuts, washers, gaskets, and electrically insulative sleeves. Such joints are typically expensive and are labor intensive to assemble and install due to the numerous parts which comprise same. During installation, and as seen in FIG. 1, the flange union joint must be aligned in a given orientation relative to a gasket to facilitate the proper seating of the gasket and substantially leak-free operation of the joint. The assembly procedure is somewhat complicated and involves a gradual tightening and torquing of a plurality of different bolts in a given pattern. In addition to the difficulties in installing such joints, dielectric flange union joints tend to leak over time due in part to the aging of gaskets; the loosening of bolts due to thermal expansion and contraction; and the misalignment and movement of conduits relative to the joint. Those skilled in the art will recognize that refrigerant and coolant leaks occasioned by the partial or complete failures of these flange union joints can create safety risks; damage to the surrounding equipment or environment; or loss of refrigerant system capacity.
A coupler for joining an aluminum conduit to a steel or stainless steel conduit which addresses these and other perceived shortcomings in the prior art practices is the subject matter of the present application.